1. Field of the Invention
The present invention relates to a single-electron transistor (SET) operating at room temperature and a method of manufacturing the same, and to be specific, to a single-electron transistor operating at room temperature and a method of manufacturing the same, which are capable of minimizing influence of the gate voltage on tunneling barriers and effectively controlling the electric potential of a quantum dot (QD), by forming the quantum dot using a trenched nano-wire structure and forming the gate to wrap most of the way around the quantum dot.
2. Background of the Related Art
In semiconductor technology, high-integration, high-speed, and low-power semiconductor devices are being developed in order to store a greater amount of information. The scale-down process of the semiconductor devices resulting from the development of technology inevitably encounters a physical limit. A single-electron transistor using a Coulomb blockade phenomenon, emerged at such a critical point, is expected to replace the complementary metal oxide semiconductor (CMOS) devices. Research has actively been carrying out on the single-electron transistor in order to apply it to the next-generation Tera-level integrated circuit devices.
Recently, with the rapid development of the integrated circuits, computers, portable terminals, etc., having a high degree of an information processing function, are being spread. Such equipments with the high functionality require semiconductor devices with low power consumption, together with a high degree of integration density, because they require high power consumption.
One of the technologies developed in order to comply with these needs is the single-electron transistor. The single-electron transistor is advantageous in that it can greatly reduce power consumption to the microwatt level because it can control the ON/OFF switching current using one electron.
The single-electron transistor, however, has the following problems.
1) The single-electron transistor requires a fine electrode structure in order to efficiently control electrons because it controls one electron using the physical property called Coulomb blockade which is enhanced in a nano-scale quantum dot.
2) The single-electron transistor must include a tunneling barrier between the quantum dot and the source (and also the drain) because it uses a tunneling phenomenon. The tunneling barrier is naturally formed by a pattern-dependant oxidation (PADOX) process when a gate oxide film is formed, making it difficult to intentionally control the height and width of the tunneling barrier. Although intentional tunneling barriers may be formed using a depletion gate, it is difficult to improve the operating temperature of the device because there is a limit in reducing a total capacitance of a quantum dot.
3) The gate is used to control the electric potential of a quantum dot. Here, a conventional single-electron transistor is operated only at low temperature because the tunneling barriers are influenced by the gate.
4) In particular, the gate is formed to cover the source and the drain region as well as the quantum dot. Thus, the gate voltage not only changes the electric potential of the quantum dot, but also influences the tunneling barriers formed on the left and right sides of the quantum dot.
5) When the gate voltage increases as described above, the height of the tunneling barriers is lowered. Consequently, the peak-to-valley current ratio (PVCR) characteristic of Coulomb oscillation is deteriorated.